An expansion coupling connecting a first pipe to a second pipe is described which includes a bellows section which is fixedly held between a first and second pipe and has a protective sliding sleeve which fits over the bellows section.
The use of plastic pipe in all forms of construction is rapidly expanding. Plumbing codes now allow for large diameter pipes from sizes of from three inches up to eight inches or greater to be used as sewer pipes, vent pipes, drain pipes and the like. As with all pipes these large diameter plastic pipes are subject to expansion-contraction forces introduced from several sources.
A long length of pipe will itself be subject to thermoexpansion. Additionally, when a long length of pipe is used within a structure and is fixed to opposing points within that structure, when the structure expands or contracts because of thermo effects, if the pipe is fixed at the two points to the structure, expansion of the structure will introduce strain into the pipe or at the joining points.
To accommodate expansion in pipes it is possible to telescope one piece of pipe into a second; however, this requires for very accurate sizing of the pipe so that leaks will not develop at such a joint. Such accurate sizing is expensive which detracts from one of the main advantages of plastic pipe.
In high rise structures it has been found that it is necessary to incorporate an expansion joint at least approximately every 20 to 30 feet for vertically running pipe. It would be further possible to connect these sections of plastic pipe with a simple bellows. However, when many sections of pipe are connected, large pressure heads can develop in these pipes. If a simple bellows connection was used the pressure developed in the pipe could distort the bellows section outwardly and could rupture them.